The invention relates to an impact calibration tool for use in a loose parts monitoring system of the type used in an operative nuclear steam supply system (NSSS) to avoid the potential of a long shutdown to repair reactor internals. There is a danger, especially immediately following an outage, that debris in the form of pieces of repair material or tools may remain in the reactor and move with the circulating fluids. Also, it has been known that unsecured fasteners and other parts can vibrate due to this flow. Depending on the mass and velocity of these items, which for convenience are labelled "loose parts", they typically create a vibration frequency of fairly normal distribution in the range of 0.1 to 100 KH.sub.z with the majority of loose parts producing frequencies in the range of 1.0 to 10 KH.sub.z.
Loose parts monitoring systems typically are used for detecting, locating and characterizing metallic loose parts in both reactors and steam generators. For a better understanding of these systems, see papers such as: Thompson, J. P., et al, "STOCHASTIC TREATMENT OF LOOSE PART IMPACT SIGNALS", American Nuclear Society, 1983 Winter Meeting; Lubin, B. T., et al, "STATISTICAL ANALYSIS OF LOOSE PART MONITORING SYSTEM SIGNALS TO DIAGNOSE THE PRESENCE OF A LOOSE PART ON THE SECONDARY SIDE OF A PWR STEAM GENERATOR", jt. ASME/IEEE Power Generation Conference, October 1986; and the bibliography papers listed therein.
In order to determine whether loose parts are stationary or roving parts, changes in signals which can indicate change in condition of the suspected loose part are recorded.
The typical equipment set up for monitoring an NSSS utilizes a series of accelerometers (transducers) mounted to record impulse-type signals that could be caused by the impact of a loose part. These signals previously have been calibrated in terms of the response at the accelerometer location to the impact energy of a gravity driven weight impacting the structure at a known location relative to the accelerometer, expressed in "g's" of acceleration. USNRC, Regulatory Guide 1.133 (Ref. 1) establishes minimum functional requirements for a loose parts monitoring system.